cluster - clusplot.default (PR#1249)

The following code in clusplot.default (package cluster) is in error:

x1 <- cmdscale(x, k = 2, eig = TRUE)
        var.dec <- sum(x1$eig)/sum(diag(x1$x))
        if (var.dec < 0)
            var.dec <- 0
        if (var.dec > 1)
            var.dec <- 1
        x1 <- x1$points

x1 has components with names "points" and "eig", not "x", so
sum(diag(x1$x)) returns 0, the division gives Inf which is later replaced
by 1.
So in the plot it is reported (always) that "These two components explain
100%
of the variability".

Besides, is it reasonable that sum(NULL) returns 0 without at least a
warning?

Another small point about the cluster package: it loads automatically
mva, but that is not mentioned in the Depends field in the description file.